Factors associated with chronic kidney disease severity among Japanese community-dwelling older adults: A cross-sectional study

• Hypertension was strongly associated with lower eGFR categories among aged ≥65 years. • Severely reduced-eGFR was associated with lower protein-related dietary intake. • Further protein restriction may be detrimental among older adults with reduced eGFR. Chronic kidney disease (CKD) is a major health issue in older adults. This study examined associations between kidney function categories based on estimated glomerular filtration rate (eGFR), lifestyle-related diseases, and sarcopenia-related conditions in community-dwelling older adults. This cross-sectional study included 251 community-dwelling Japanese adults aged ≥65 years. Baseline characteristics, including age, sex, comorbidities, and lifestyle factors, were assessed. Kidney function was classified into three eGFR-based categories: higher-eGFR (≥60 mL/min/1.73 m²), moderately reduced-eGFR (45–59 mL/min/1.73 m²), and severely reduced-eGFR (<45 mL/min/1.73 m²). Sarcopenia, nutritional status, dietary intake patterns, and physical activity were evaluated. The Kruskal–Wallis test was used to compare dietary intake patterns among the three groups. Logistic regression analyses examined associations between eGFR categories and clinical characteristics, including dietary intake patterns, comparing (1) higher-eGFR vs. moderately reduced-eGFR and (2) higher-eGFR vs. severely reduced-eGFR, adjusting for age and sex. Protein-related dietary intake patterns differed significantly among the three eGFR categories, with lower scores observed in the severely reduced-eGFR group compared with the higher-eGFR group. In logistic regression analyses, hypertension was independently associated with moderately reduced-eGFR (odds ratio [OR] = 2.30). Hypertension (OR = 4.53) and lower protein-related dietary intake patterns (OR = 2.88) were independently associated with severely reduced-eGFR, whereas sarcopenia was not. Lower eGFR levels were strongly associated with hypertension, and lower protein-related dietary intake patterns were observed in more advanced kidney function categories. Excessive dietary protein restriction may warrant careful reconsideration among older adults with severely reduced eGFR.